Flash Flood in Wisconsin, September 1, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
355 PM CDT SAT AUG 31 2002

THE MAIN FORECAST CHALLENGE DURING THE NEXT 24 HOURS CONCERNS HEAVY
RAIN CHANCE.

ALTHOUGH NOT ALL INGREDIENTS HAVE COME TOGETHER FOR EXCESSIVE
RAINFALL...ENOUGH ARE PRESENT FOR ISSUING A FLOOD WATCH FOR PART OF
OUR CWA. MESOETA/ETA/AVN ALL BRING PWAT VALUES UP TO ABOUT 1.60
INCHES BY 12Z SUNDAY WITHIN A DIFFLUENT THICKNESS PATTERN WHICH
DYNAMICALLY IS OFTEN ASSOCIATED WITH A BACKBUILDING TRAIN ECHO
EFFECT. THE ONE INGREDIENT WED LIKE TO SEE IN PLACE FOR HEAVY
RAINFALL IS A TROPICAL PLUME ON THE MOISTURE CHANNEL IMAGERY. WHILE
A FRACTURED VARIETY IS EVIDENT FROM THE WESTERN DAKOTAS SOUTHWEST
INTO SOUTH CALIFORNIA...IT REMAINS UNCERTAIN IF IT WILL LINK UP WITH
THE EXPECTED AREA OF CONVECTIVE DEVELOPMENT OVER WEST CENTRAL
MINNESOTA LATER THIS EVENING.

LOCALLY HEAVY RAINFALL IS POSSIBLE OVER EAST CENTRAL MINNESOTA INTO
WESTERN WISCONSIN LATER SUNDAY INTO EARLY SUNDAY EVENING.  FOLLOWING
WHATEVER MCS THAT PASSES ACROSS THE AREA LATER TONIGHT AND
SUNDAY...ANOTHER TROUGH ARRIVES EARLY MONDAY FOR GENERATING MORE
CONVECTION ON LABOR DAY.

WE DRY OUT TUESDAY THROUGH THURSDAY AND THEN THE PRECIPITATION
CHANCE RETURNS AGAIN ON FRIDAY AND SATURDAY.

.MSP...FLOOD WATCH FROM MIDNIGHT UNTIL NOON SUNDAY TO THE NORTHWEST
OF A  MML...LJF...CBG LINE

WET

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-011300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
105 AM CDT SUN SEP 1 2002

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER CENTRAL
MINNESOTA THIS MORNING...SPREADING INTO SOUTH CENTRAL MINNESOTA
AND WEST CENTRAL WISCONSIN LATE THIS MORNING AND AFTERNOON.  THE
AREA IS ROUGHLY ALONG AND SOUTH OF A LINE FROM ALEXANDRIA TO STAPLES
TO MORA...TO RICE LAKE AND LADYSMITH IN WISCONSIN.  OTHER CITIES
INCLUDED IN THE SLIGHT RISK ARE THE TWIN CITIES...ST. CLOUD...
REDWOOD FALLS...MANKATO...CAMBRIDGE...ALBERT LEA...AND IN
WISCONSIN...HUDSON...EAU CLAIRE AND DURAND.

EARLY THIS MORNING...STRONG THUNDERSTORMS WERE TRACKING EAST THROUGH
NORTHEAST SOUTH DAKOTA AND SOUTHEAST NORTH DAKOTA TOWARD WEST
CENTRAL MINNESOTA.  THESE THUNDERSTORMS WILL SPREAD INTO THE
STATE BY 3 AM.  THEY ARE EXPECTED TO WEAKEN THROUGH THE MORNING...BUT
MAY STILL PRODUCE SOME LARGE HAIL OR DAMAGING WINDS IN PARTS OF
CENTRAL MINNESOTA THROUGH 8 OR 9 AM.  IN ADDITION...HEAVY RAINFALL IS
ALSO A POSSIBILITY...WITH ONE TO THREE INCHES OF RAIN POSSIBLE...
RESULTING IN STREET FLOODING.  A FLOOD WATCH REMAINS IN EFFECT FOR
PARTS OF CENTRAL MINNESOTA UNTIL NOON.

SHOWERS AND THUNDERSTORMS ARE EXPECTED TO SWEEP ACROSS CENTRAL
INTO SOUTH CENTRAL MINNESOTA AND WEST CENTRAL WISCONSIN LATER
THIS MORNING AND AFTERNOON.  A FEW OF THESE THUNDERSTORMS MAY
STRENGTHEN...AND BECOME SEVERE ACROSS THESE AREAS THIS
AFTERNOON AND EVENING.  THE MAIN SEVERE WEATHER THREATS WILL BE
LARGE HAIL AND DAMAGING WINDS.

SEVERE WEATHER SPOTTERS IN THESE AREAS MAY BE NEEDED LATE TONIGHT
AND SUNDAY.  ALL INTERESTS SHOULD LISTEN FOR LATER STATEMENTS ON THIS
SEVERE WEATHER POTENTIAL.

MBK